Hydraulic mine roof supporting devices



Jan. 5, 1965 c. M. FRYE ETAL 3,164,066

' HYDRAULIC MINE ROOF SUPPORTING DEVICES Filed March 20, 1961 5 Sheets-Sheet 1 INVENTQRS Com m, Ft/E BY #rRpA'n-r muuml flu/4P9 /-/-B. WIRDGR MPM,

' ATTORNEYS.

Filed March 20, 1961 Jan. 5, 1965 c. M. FRYE ETAL 3,164,066

HYDRAULIC MINE ROOF SUPPORT ING DEVICES 3 Sheets-Sheet 2 INVENTQQ-S "coun! M. F Y HEttst-r M -B u ATTORQIE! t Colin PA.

United States Patent Cfiice arias Patented Jan. 5, 1965 3,164,966 HYDRAULHC MENE BEVEQE Fr c St. c-n, near Ten/lie; Her-l; urn, Draaes Sludge, Eeidngton, Per-shore, and d H. B. Winder, Presthury, Cheltenhani, England, assigners to Dowty Egnipment Liniited, Aslschurch, England, a British company Filed Mar. 2t 1961, Ser. No. $6,745 lairns priority, application Great Britain, Mar. 23, 1959, 19,343/ so 8 Gains. (ill. file-41?) This invention relates to mine roof supporting devices of the kind having two interconnected prop units, each comprising at least one hydraulic prop having a cylinder and piston enclosing a pressure chamber in which each unit can be contracted, advanced to a new position, and extended into roof supporting engagement while the other unit is maintained extended, the advance of the contracted unit being effected by one of more doubleacting hydraulic jacks or similarly operating mechanism acting directly or indirectly between the two units.

The invention is particularly concerned with valve mechanism having independent controls for the prop or props of the two units, and its main object is to ensure that both prop units cannot be inadvertently contracted at the same time. The condition to be avoided by the present invention could permit deterioration of the mine roof unless the roof is supported by other means to en ahle the two units to be fully withdrawn for use in another location in the mine.

According to the invention a device of the kind referred to comprises a selector valve for each prop unit adapted for connection with a source of pressure fluid and operative to control the flow or" pressure fluid to and the exhtust fluid from the prop or props of the unit through conduit means which extend between the selector valve and the prop or props, an isolating valve in said conduit means normally closed to prevent contraction of the prop or props of the unit, and means responsive to fluid setting pressure in the prop or prop-s of the other unit acting under said fluid setting pressure to open the isolating valve whereby the prop or props of the first mentioned unit can be contracted upon appropriate operation of the selector valve.

t is desirable that the pressure responsive means shall not open the isolating valve until the prop o-r props of the other unit are fully extended and the pressure therein has risen to substantially that of the source.

The invention is illustrated in the accompanying drawings, in which:

FIGURE 1 shows a mine roof supporting device comprising a prop-supported shield adapted to support the roof of a mine roadway over a mining machine; and

FEGURES 2A and 2B are a hydraulic circuit showing the manner in which the props of the device are operated.

The device in FIGURE 1 comprises two overlapping and interconnected units shown generally at ill) and ll. The unit it comprises a pair of transverse roof bars 12 and 13 carrying a plurality of longitudinal root bars 14 in the form of a rectangular grid, and the transverse roof bars 12 are carried on the ends of four vertical hydraulic props 15 whose lower ends rest on the ground.

The other unit 11 likewise comprises transverse roof led has 1.6 carrying a plurality of longitudinal roof bars 17 and four vertical hydraulic props 18 arranged at the corners of the structure. The two units it) and 11 :are arranged with their longitudinal roof bars 14 and 17 overlapping as shown and the extent of overlap can be varied by simultaneous operation of a pair of advancing jacks which comprise piston rods 19 attached to the transverse bar 112 of the unit ill and cylinders 21 attached to the transverse bar 16 of the unit 11.

The manner in which the props 15 and 18 are operated is shown in the circuit diagram of FIGURES 2A and 213. ()ne of the props 15 and one of the props 18 are shown in the diagram and it is to be understood that each illustrates a set of four in FIGURE 1 which are connected in parallel for simultaneous operation. The prop 15 is double-acting and comprises a cylinder 22 having a piston 23 slidable therein on. the end of a ram tube 24 which carries a prop head 25. A connecting point 26 in the prop head 25 leads to a central tube 2'7 which opens through the piston 23 into a pressure chamber A second connecting point 29 opens into an annular passage formed between the tubes 24 and 27 and outwardly through radial holes 31 in the ram tube into an annular chamber 3-2 above the piston Extension contraction of the prop 15 is controlled by a four-Way selector valve 33 which is mounted in a suitable position on the unit fill with connections to a source of pressure and a return line, not shown. The four-way valve 33 is of conventional form having a cylindrical valve bore 34 with a central pressure port 35 therein, two interconnected low pressure return ports 35 and 37 axially spaced from the pressure port 335, and two service ports 33 and 39 disposed between the pressure port 35 and the return ports as and 37 respectively. The valve is of the closed centre type having a valve spool 41 which in its central postion isolates the pressure port 35 but which can be displaced by a pivoted handle 42 against the load of a spring 43 to connect one of the service ports 38 or 39 with pressure and the other with return, or vice versa. The service ports lead by way of passages 44, 45 to service conduits 4s and 47 which in turn lead to the connecting points 2% and 26 respectively in the prop head 25. A known form of hydraulic lock is arranged in the passages 4-4 and 45 comprising poppet type non return valves 48 and 49 which open against spring-load under fluid flow from the valve 33 to the prop 15, and a double-acting shuttle piston 5i which is of larger area than the poppet valves 48 and as and which is provided with push pins 52 and 53 acting to open either valve 48 or 4?: under fluid pressure applied in turn to opposite sides of the piston 51. The hydraulic lock ensures that the prop 15 can sustain a higher fluid pressure in the chamber 28 under roof load than is supplied by the source to the pressure port 35, without yielding of the props 14. The prop l5 can nevertheless be contracted by displacing the valve spool 41 to admit fluid pressure into the passage 44, past the non-return valve 48 into the conduit 46 and by way of the connecting point 29 to the annular chamber 32. The pressure in the passage .4 also acts on the left hand side of the shuttle piston 51 causing the push pin 53 to open the non-return valve 49 whereby fluid from the pressure chamber 28 of the prop can escape to return. The

shuttle piston 51 acts similarly under prop extension anemone pressure in the passage 45 to open the valve 48 by the push pin 52.

A similar four-way selector valve 54 controls the four props 13 of the unit 11 and like elements of the valve are similarly numbered so that the preceding description is applicable also to the valve As thus far described, the two valves 33 and 54 are capable of independent operation so that it would be possible by appropriate operation of the handles 42 to contract both sets of props l5 and 18 simultaneously, and the means by which this is prevented automatically will now be described. Either supply passage 44 or 45, but for preference as shown the supply passage 44 of each valve leading from the service port 38 ultimately to the annular chamber 32 of the prop or it; includes an isolating valve, which is generally numbered 55 in the selector valve 33, and 56 in the selector valve 54. This isolating valve comprises a cylindrical bore 57 of larger diameter than and intersecting the passage 44, with a plunger 58 slidable therein under the load of a spring 59 normally to close the passage 44. The bore 57 leads to a bore 625. of reduced diameter in which a piston s2 is slidable, this piston 62 being connected to the plunger 58 by a stem 63. The portion of the bore 61 behind the piston 52 is connected by a pipe 64 to the passage in the selector valve assembly 54 beyond the non-return valve 4?. Similarly, the cylindrical bore 61 behind the piston 62 in the isolating valve 56 is connected by a pipe 64 with the passage 45 beyond the non-return valve th in the selector'valve assembly 35.

It will then be evident that each piston 62 is responsive to the fluid pressure in the pressure chambers of the props of the other unit. If for example, there is pressure in the pressure chambers 23 of the props 1?, this pressure is communicated through the conduit 47, passage 45 and pipe 64 to the bore 61 behind the piston 52 in the selector valve 33. The pressure overcomes the load of the spring 59 to displace the plunger 53 and open the passage 44, whereby the props 15 can be contracted by turning the handle 42 in an anticlockwise direction to displace the valve spool 41 to the right, thus connecting the pressure port 35 with the service port 38. If on the other hand, the props 18 are collapsed so that there is no pressure in the pressure chamber 28 then there will be no pressure behind the piston 62 and the spring 59 will accordingly extend the plunger 58 to close the passage 44 of the valve 55. The isolating valve 56 in the selector valve assembly 54 of the other unit is similarly responsive to pressure in the pressure chambers 28 of the props 15. The props 15 and 18 in FIGURES 2A and 2B are shown extended with liquid pressure in their pressure chambers 28 acting on the pistons 62 to hold both isolating valves and 56 open. When the props 15 and 18 are contracted both isolating valves 55 and 56 are closed because there is no pressure in the pressure chambers 28 to act on their respective pistons 62. 7

Each isolating valve 55 or 56 is provided with a manual over-ride in the form of a stem 65 projecting from the valve casing, and a shackle 66 on the projecting end of the stem. The shackle 66 may be pulled to open the isolating valve 55 or 56 when it is desired to extend both units for the first time, or when it is desired to contract both units so that the roof supporting device can be moved as a whole to a new location. F

The piston 62 is made smaller in diameter than the plunger 58 so that for a given valve-operating pressure in the prop chamber 28 the spring 59 can be kept down to a compression which can be more readily overcome by a pull on the stem 65.

We claim as our invention:

1. In combination, a pair of double-acting hydraulic motors arranged in parallel relationship to one another, a pair of selector valves each hydraulically connected to the opposite sides of an individual motor to apply bydraulic pressure from a pressure source in alternate fashion to such sides, a pair of isolating valves in the hydraulic connections between the selector valves and corresponding sides of the motors, said isolating valves being biased to close the connections against the application of pressure to the aforesaid corresponding sides of the motors, and responsive to a predetermined pressure thereon to open the connections against such bias, and a pair of cross controls between the isolating valves and the other sides of the motors, each of which interconnects the aforesaid other side of one motor with the isolating valve in the hydraulic connection to the other motor, to communicate the pressure on the other side of the one motor to the isolating valve and to cause the latter to open the connection when such pressure reaches the predetermined magnitude.

2. In combination, a pair of double-acting hydraulic motors arranged in parallel relationship to one another, a pair of selector valves each hydraulically connected to the opposite sides of an individual motor to apply hydraulic pressure from a pressure source in alternate fashion to such sides, a pair of isolating valves in the hydraulic connections between the selector valves and corresponding sides of the motors, a pair of closure members urging the isolating valves to close the connections against the application of pressure to the aforesaid corresponding sides of the motors, a pair of valve controls operable to cause the isolating valves to open the connections against the bias of the closure members, and a pair of cross controls between the valve controls and the other sides of the motors, each of which interconnects the aforesaid other side of one motor with the valve control operable on the isolating valve in the hydraulic connection to the other motor, to operate the valve control and thereby open the connection to said other motor, when the pressure in the other side of the one motor reaches a predetermined magnitude.

3. The combination according to claim 2 wherein the valve controls are hydraulically operated and the cross controls include a pair of hydraulic connections between the valve controls and the other sides of the motors.

4. The combination according to claim 2 wherein the isolating valves are spring-biased to close the connections and the valve controls take the form of piston controls on the isolating valves which are responsive to a pressure of the aforementioned magnitude to cause the isolat ng valves to open the connections against the bias of the springs.

5. The combination according to claim 4 wherein the piston controls are hydraulically operated and the cross controls include a pair of hydraulic connections between the piston controls and the other sides of the motors.

6. The combination according to claim 4 further com prising a pair of operators controls which are operable by hand to cause the isolating valves to open the connections against the bias of the springs.

7. The combination according to claim 2, wherein the hydraulic motors take the form of double-acting hydraulic props.

8. In a mine roof supporting device comprising two interconnected support units each including at least one hydraulic prop having cylinder and piston members together enclosing a pressure chamber, hydraulic control mechanism comprising for each support unit a selector valve adapted for connection with a source of pressure iiuid, conduit means extending between the selector valve and the prop, said conduit means including rst and second passages through which fluid pressure from the source is selectively admissible upon reversible operation of the selector valve to efiFect extension and contraction respectively of the hydraulic prop, an isolating valve including a movable valve element disposed in opening and closing relationship with at least one of said passages, loadin means disposed against the movable valve element in the valve closing sense, fluid pressure responsive means disposed against the movable valve element in the valve opening sense, and a fluid pressure connection extending between said fluid pressure responsive means and the pressure chamber of a hydraulic prop in the other of said two support units, whereby fluid setting pressure in the pressure chamber of the last mentioned prop is operable upon the fluid pressure responsive means to open said isolating valve, the loading means being a spring disposed at one end of the movable valve element, the fluid pressure responsive means being a piston disposed at the opposite end, and the movable valve element including a stem which extends externally from the valve beyond the spring and which is adapated for manual operation under tension against the load of the spring.

References Cited by the Examiner UNITED STATES PATENTS Temple 60-52 X Gardiner 91-411 Livers 91--412 Fehring 6097 X Joy 61-45.2 X Presnell 91412 Bamber 91412 FRED E. ENGELTHALER, Primary Examiner.

WILLIAM I. MUSHAKE, Examiner. 

1. IN COMBINATION, A PAIR OF DOUBLE-ACTING HYDRAULIC MOTORS ARRANGED IN PARALLEL RELATIONSHIP TO ONE ANOTHER, A PAIR OF SELECTOR VALVES EACH HYDRAULICALLY CONNECTED TO THE OPPOSITE SIDES OF AN INDIVIDUAL MOTOR TO APPLY HYDRAULIC PRESSURE FROM A PRESSURE SOURCE IN ALTERNATE FASHION TO SUCH SIDES, A PAIR OF ISOLATING VALVES IN THE HYDRAULIC CONNECTIONS BETWEEN THE SELECTOR VALVES AND CORRESPONDING SIDES OF THE MOTORS, SAID ISOLATING VALVES BEING BIASED TO CLOSE THE CONNECTIONS AGAINST THE APPLICATION OF PRESSURE TO THE AFORESAID CORRESPONDING SIDES OF THE MOTORS, AND RESPONSIVE TO A PREDETERMINED PRESSURE THEREON TO UPON THE CONNECTIONS AGAINST SUCH BIAS, AND A PAIR OF CROSS CONTROLS BETWEEN THE ISOLATING VALVES AND THE OTHER SIDES OF THE MOTORS, EACH OF WHICH INTERCONNECTS THE AFORESAID OTHER SIDE OF ONE MOTOR WITH THE ISOLATING VALVE IN THE HYDRAULIC CONNECTION TO THE OTHER MOTOR, TO COMMUNICATE THE PRESSURE ON THE OTHER SIDE OF THE ONE MOTOR TO THE ISOLATING VALVE AND TO CAUSE THE LATTER TO 